Under which one of the following condition will the two planes x+y+z=7 andαx+βy+γz=3, be parallel (but not coincident)?

[c] Given equation of planes are: x+y+z=7 and αx+βy+γz=3 For these planes to be parallel, coefficients of x, y and z should be same i.e. ⇒α=β=γ